An elevator installation with a shaft in which two elevator cars arranged one above the other are movable upwardly and downwardly, wherein the shaft has a plurality of shaft doors and the elevator cars each have at least one elevator car door, is already known from the specification EP 1 618 059 B1.
In order to avoid potentially risky operating situations the elevator installation has a safety device, which comprises so-called safety circuits and by means of which safety-relevant components such as shaft doors, elevator cars doors, shaft limit switches, buffers and speed cable, are monitored by sensors, which are each coupled with a respective switch. The switches arranged in a safety circuit are connected in series, wherein a closed switch indicates a safe state of the component of the elevator installation. Opening of a single switch is sufficient for interruption of the safety circuit, whereupon at least the elevator drive is interrupted.
Each of the elevator cars of the elevator shaft has an individual safety circuit which monitors the respective travel region of the elevator car so that opening of a safety circuit in defined cases has no immediate effects on operation of the other elevator cars, whereby a part of the transport capacity of the elevator installation is maintained.